The present invention relates to rotary encoders.
In many cases, it is necessary to determine, in an absolute manner, the position of a shaft within one rotation, as well as the number of rotations. For this purpose, multiturn rotary, encoders are used as described, for example, in International Published Patent Application No. WO 99/57522, German Published Patent Application No. No. 28 17 172 and German Published Patent Application No. 195 34 995.
Such rotary encoders should have a compact design, and on the other hand, should exhibit high measuring accuracy. According to the rotary encoder described in German Published Patent Application No. 28 17 172, to provide a space-saving design, the code disks, driven via a step-down gear, are positioned within the peripheral area of the input code disk. The detector elements for scanning the input code disk and the code disks, driven geared down relative thereto, are arranged on different printed circuit boards.
In the case of the multiturn rotary encoder described in German Published Patent Application No. 195 34 995, the detector elements for scanning an input code disk and code disks driven geared down relative thereto, are arranged on one side of a shared printed circuit board. To achieve this, the code disks, driven in a geared-down manner, are arranged spatially next to the input code disk, which increases the size and hinders the design, since no modular design is possible.
It is an object of the present invention to provide a multiturn rotary encoder which has a compact configuration, permits a modular type of construction and has high angular resolution.
The detector devices of the input code carrier and of the code carriers driven geared down relative thereto may be applied on a single surface of a printed circuit board in a joint process step.
The opposite surface of the printed circuit board is available for further components for the signal processing, and may be fitted with components according to a further method. Moreover, at least substantially the entire periphery of the rotary encoder may be used for the coding of the input code carrier, thereby permitting a maximum angular resolution as a function of the entire periphery of the rotary encoder.